1. Field of the Invention
This invention relates to lasers and, in one aspect to a mirrorless laser.
2. Description of Related Art
Certain prior art lasers are made with expensive surface coating technologies and are assembled by skilled technicians with the need for precise adjustments. Certain prior art lasers use reflective surface coatings which wear out, especially when used with infrared laser wavelengths. Certain prior art lasers have mirrors which are adjusted to a precise alignment to function well. Such lasers often are not optimally useful in applications where there is need for high portability or long functional lifetimes. There has long been a need for a laser which overcomes these problems and disadvantages. There has long been a need for a laser which may be made without coatings and without adjustable parts so that the cost of assembly is greatly reduced, so that the ruggedness of products using the laser is improved, and so that the functional lifetime of laser devices using the design is extended as compared with certain commonly available laser devices.
A typical laser has a light source, a lasing material, and a set of reflectors, Most solid state laser are derived from the ruby laser design consisting of a rod of crystalline ruby material surrounded by a helically-formed, gas-filled, high intensity lamp, with mirrors placed a precise distance from, or in contact with, or coated onto, the surfaces of the ruby material. One mirror has either a hole or a reduced reflectance relative to the other. Light is injected from the lamp into the laser material initiating the discharge of photons from impurities in the crystal. These photons travel between the two mirrors producing a harmonic amplification. The amplified laser beam escapes the system through the hole or area of reduced reflectance. The ruby crystal can be replaced with various lasant materials to produce different wavelengths of laser light. These materials include yttrium-aluminum-garnet (YAG) which will include chemical impurities to modify the resultant wavelength of the laser. These traditional laser designs require the use of precisely made mirrored surfaces. These surfaces are generally created by coating the surfaces with a thin coating of reflective material. If separate mirrors are used, they must be placed precisely with respect to the optical axis of the laser rod, with respect to each other, and with respect to the desired output location of the device. If the mirrored surfaces are misaligned by handling of the device, the effective function, and efficiency of the device is decreased. The reflective mirror surfaces may also be produced by coating them onto the surface of a laser crystal. In each case, very expensive and highly complex machinery is required to create a smooth, homogeneous coating of controlled thickness. These coatings may be damaged by photochemical effects of continued exposure to the laser light, especially light of infrared wavelengths. This incremental damage reduces the effective lifetime of the laser.